Process for treating textiles



April 26, 1955 L. b. sin/AN 2,706,845

PROCESS FOR TREATING TEXTILES Filed July 26, 1954 FIG]. I 2 1 lNVENTCi LEWIS DELMAR SWAN ATTORNEY United States Patent O PROCESS FOR TREATING TEXTILES Lewis Delmar Swan, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application July 26, 1954, Serial No. 445,498

6 Claims. (Cl. 261) This invention relates to a process for treating textiles. More specifically it is concerned with a process for the reduction of fabric pilling, particularly upon a fabric made from yarn containing synthetic thermoplastic fiber staple.

The production of pills upon fabrics produced from spun yarn containing synthetic fibers is a problem familiar to the trade. In the normal wear of a fabric, particularly one made from a yarn containing synthetic staple, the fibers, particularly at the exposed crown of the yarn, begin to work free. They gradually lengthen, fuzz and tangle or cable and eventually ball up into what is commonly known as a pill. The fuzz formation, which is the first step in the development of pilling, is particularly acute with fabrics made from spun yarn containing a synthetic fiber component. These synthetics are smooth and, having relatively high tenacity, any pills which form are not easily abraded away from the fabric surface. Thus, under rubbing action, such as occurs particularly on wearing and washing, these relatively strong, smooth fibers tend to work their way out of the yarn bundles. Pilling occurs after fuzzing becomes pronounced. Fabrics from yarns containing staple components produced from polyester, and/or polyamide polymers are susceptible in this respect. However, the phenomenon is one which is experienced with practically all fibers, both natural and synthetic, including those produced from acrylic type polymers. It is apparent that any treatment which can be given to the fabric to prevent fuzzing will lessen pill formation.

It is an object of the present invention to provide a process for the reduction of the propensity of fabric to pill.

Another object is to provide a pill resistant fabric produced from yarn containing synthetic, thermoplastic fiber, either alone or in blends with other fibers.

These and other objects will become apparent in the following description and claims.

By the term fabric produced from a yarn containing synthetic, thermoplastic fiber is meant any woven, knitted, matted, felted or other type of fabric with a propensity to pill as described above, which is produced from yarn at least one component of which is a fiberforming thermoplastic synthetic polymer, particularly as described in greater detail hereinafter.

In accordance with the present invention the surface of the fibers in the exposed crown of the yarn are first disfigured by the random flattening of their cross-sectional dimensions and they are thereafter locked within the fabric structure by compression with adjacent fibers at the points of asperity. The fibers in yarn crowns and their exposed ends can be conveniently disfigured by brushing the surface of the fabric gently with a rapidly revolving brush having bristles which provide a heel to toe, non-plucking contact as will be described in greater detail hereinafter. The locking of the disfigured fibers within the fabric structure is conveniently obtained by shrinking. The shrinkage causes a simultaneous retraction of, and slight increase in the twist of the yarn. The combination of these actions, i. e., retraction and increased twist, compresses adjacent filaments around points of fiber asperity, thereby locking the fibers within the fabric structure.

The invention will be more readily understood by reference to the drawings.

Figure l is a diagrammatic representation showing the relative motion of a single brush bristle and a moving surface of fabric, the bristle being of a structure which provides a heel to toe impact with the fabric as indicated.

Figure 2 illustrates a system suitable for the brushing of a width of fabric in accordance with the first step of the process of the present invention wherein the brush is applied to a relatively wide area of fabric to be referred to hereinafter as the gap contact technique.

Figure 3 is a representation similar to that of Figure 2 wherein the heel to toe brushing action of the revolving brush against the fabric occurs along a thin line of fabric width to be referred to hereinafter as the point rest contact technique.

Figure 4 is an illustration of several loose fibers showing typical disfiguration produced by the brushing action.

To better understand the present invention consider the illustration of Figure 1 wherein a brush bristle 1 is shown. It has a point or toe 2 at the free end of its shank, the point being preceded as the bristle progresses in the direction indicated, by a leading edge or foot 3 which terminates along the shank at the heel 4. The sweep of the bristle 1 across the surface of the fabric 5 in the general relative directions indicated permits the toe 2 to be led into the fabric surface by the foot 3, thus providing a smoothing or polishing action by the toe rather than a plucking action. This is what is meant by heel to toe brushing.

Figure 2 illustrates a brushing system useful in the present process wherein a revolving brush 6, contacts a relatively large area or gap of fabric 5. The fabric is removed from braked supply roll 7 over spreader roll 8, fixed guide 9 and adjustable guide 10 and is collected at drive roll 11. This brushing system provides the gap contact technique.

The brushing system of Figure 3 provides the edge rest contact technique. Its operation is similar to that described in Figure 2. However, contact of revolving brush 6 is made with fabric 5 along an edge provided by adjustable edge rest 12. The fabric moves from supply roll 7 to drive roll 11 over spreader roll 8 and fixed guide 9. Contact angle adjustment idlers 13 are provided on each side of edge rest 12.

Figure 4 is a magnified view of several fibers removed from the surface of a fabric after it has been subjected to heel to toe brushing as taught in the present specification. The fibers which originally possessed a smooth profile and were of round cross section have been disfigured by fiattening of their cross-sectional dimensions producing nobs, indentations and other irregularities.

The structure of brush, such as the number and the spacing of the noggs, is not critical as long as the heel to toe impact is obtained. The bristles are conveniently of round cross section but not necessarily so. Normally the material of their construction is a metal, preferably steel, although other materials are suitable. The bristle should possess sufficient stiffness to develop frictional heat at the fabric surface and thereby soften the thermoplastic fibers. However, adequate bristle fiexibility to avoid fabric tearing must be present. Such a brush can be made by wrapping a cylinder with card clothing for a fancy brush of a roller card. The card clothing may have any of the conventional designs, i. e., the noggs may be straight and be mounted at to the backing, they may be of the angularly mounted variety or of the bent knee structure. it is not essential that the brush be rotary in form. Nor is it essential that both brush and fabric be in motion during the brushing as long as the relative motion provides the proper bristle impact. A satisfactory brush is in the form of a 15 inch diameter cylino'er, 48 inches long with bristles made from fancy roll card clothing, 36 gauge steel wire of round cross section, A inch staple. It contains four rows of noggs in a 4 twill pattern, 18 noggs to the inch, duck'and leather ply foundation with the nogg mounted 90 to the backing. This is a standard clothing for a fancy roll of a roller card.

Optimum contact speed and period between fabric and brush will vary widely depending upon both the nature of the brush and the fabric, the pressure of contact between the moving elements and the like. In general, using the brush described above upon a twill fabric made from 30/2 cotton count yarn spun from 2 /2 inch polyethylene terephthalate 3 denier per filament having 21 singles Z twist of 16 turns to the inch and an 8 ply 20 turns to the inch, a fabric speed of two yards per minute is satisfactory where the brush is revolving about 750 revolutions per minute and a light contact pressure is maintained between fabric and brush on the gap contact technique described earlier.

A suitable alternate set of conditions involves multiple passes of the fabric at 30 yards per minute over a support providing either the gap or point rest contact against a similarly clothed cylinder 9 /2" in diameter, 80 in length, rotating at 1150 revolutions per minute.

After the surface fiber disfiguration is obtained it is necessary that the points of asperity be locked within the fabric structure. This is readily accomplished by shr1nk ing. This phenomenon tends to position points of asperity within the yarn and to cause a natural increase in the twist of each yarn. This action increases tension at crossover points, compresses adjacent yarns around the disfigured fibers and locks them in place.

All synthetic thermoplastic polymeric filamentary ma terials manufactured have the necessary retraction (i. e., at least a 23% boil-off shrinkage), and can be employed in the process of this invention to reduce pilling at fabric surfaces. These include polyamides, polyesters and polyesteramides, polyvinylidene and polyvinyl compounds and their copolymers or interpolymers, and the like.

The retraction or shrinking treatment may consist of heating by various means, as by application of Water, oil, steam, air or other fluid which is relatively inert with respect to the particular filamentary material. Retraction of the material may be accomplished with a swelling agent in addition to or in place of the heat treatment. A combination of chemical and physical treatments may be used. Any method of shortening the end-to-end length of the filamentary material without too adversely affecting the fiber structure itself is acceptable. The time of treatment may vary from a few seconds to hours, although for simplicity, times of the order of a minute or so are preferred.

The following examples are cited to illustrate the invention. They are not intended to limit it in any manner. In each example the test for pilling is performed by clamping an 8" x 10 swatch of the fabric to be tested to a sample board in such a way that a 4 x 8 surface is exposed. This surface is then brushed by a nylon bristled brush oscillating in a radius, under a load of 0.6 ounce per square inch for five minutes. It is then rubbed with the surface of a cellulosic sponge in the same manner for 5 more minutes, after which the number of pills per square inch is counted.

Example I A 2 X 2 twill fabric of 70 ends by 66 picks in the loom is woven from polyethylene terephthalate yarn spun on the modified cotton system from 2 /2 inch, 3 denier staple, to a /2 ply cotton count, with a Z twist of 16 turns per inch in the single and an S twist of 20 turns per inch in the ply. The surface of the fabric is given a light smoothing nip by a wire brush 15 inches in diameter, rotating at 750 revolutions per minute. The bristles of the brush are 36 gauge wire, A1 inch long, of round cross section and are ground to provide a heel to toe bite. This is provided by the standard clothing for a fancy roll of a roller card as previously described. The fabric is moved at a rate of 2 yards per minute in a direction opposite to that of the brush. The contact is made by the gap method using a light contact pressure.

After the brushing action the fabric is given a relaxed heat treatment in a pin tenter at 360 F. for an exposure of about 45 seconds. A shrinkage allowance of about 4% is applied in both warp and filling tractions.

Swatches of the fabric are pill-tested during the various stages of treatment with results as follows:

Pills per square inch 8 Untreated After brushing 10 After brushing and shrinking 2 After shrinkage (without brushing) 6 EXHI'HPIE II age. The finished fabric as treated shows no pills. The fabric, as produced, without brushing and shrinking exhibits 3 pills per square inch.

In general, the results herein described accrue when the shrinkage follows the brushing step. This does not imply that the two steps must be taken in direct sequence. In fact, these two steps may be introduced into the otherwise conventional operations used in finishing a fabric wherever convenient, but it is essential that the brushing treatment antedate a later shrinkage step.

Examples III to V1 inclusive listed below illustrate the effect of process variation on the pilling propensity of a 2 x 2 twill weave suiting of yarn spun from 55% polyethylene terephthalate and 45% wool. The order of the process steps and the result of the pill test is listed.

Example III This is a conventional process:

. Desize with enzyme and scour with detergent.

. Dry (room temperature).

. Shear, 3 passes each side.

. Semidecate, 2 minutes steam, 1 minute vacuum.

Pilling: 4 /2 pills per square inch.

Example IV 1. Desize with enzyme and scour with detergent.

2. Dry (room temperature).

3. Brush (using technique of Ex. I).

4. Shrink (technique of Example I at 380 F. for 45 seconds).

5. Shear, 3 passes each side.

6. Semidecate, 2 minutes steam, 1 minute vacuum.

Filling: 1 pill per square inch.

Example V A repetition of Example IV is run with the steps in the following order:

1. Brush.

. Shrink.

. Desize and scour.

Dry.

Shear.

. Semidecate.

Filling: 2 pills per square inch.

Example VI Another repetition of Example IV is run with steps as follows:

. Brush.

. Desize and scour.

Dry.

. Shrink.

. Shear.

. Semidecate.

Filling: 2 /2 pills per square inch. Example VII A plain weave batiste shirting of polyethylene tcrephthalate yarn spun from 2 /2 inch staple of 3 denier per filament is brushed in accordance with the technique of Example 1 and shrunk in a pin tenter at 380 F. for 45 seconds, relaxed. The fabric is then finished by the conventional operations of scouring, singeing, shearing, calendering and the like. 1 to 2 pills per square inch are observed on testing. The fabric finished in the normal manner but with omission of the wire brush, heat shrinkage steps, exhibits 5 to 6 pills per square inch.

Example VIII ethylene terephthalate staple and 20% hexarnethylene adipamide staple. Without further finishing other than served.

Example X A basket weave fabric of 92 ends by 88 picks in the loom is woven from a mixed yarn of 65% polyethylene terephthalate staple and 35% cotton spun on the modified cotton system to a 40/ 1 cotton count, the warp and filling yarns containing a twist of 31.6 and 28.5 turns per inch respectively. One sample of this fabric is conventionally finished and on pill testing it shows 5 to 6 pills per square inch. A second sample is wire-brushed by the gap method with one pass per face, followed by a 45 second exposure in a relaxed state to a temperature of 360 F. in an overfed pin tenter. The second sample raises between zero and 1 pill per square inch on the pills tester.

In each of Examples XI to XIII a pill test is run on the fabrics described both With and Without treatment in accordance with the present invention. The pill reduc ing treatment employed consists in each instance of two light passes with a revolving brush using the gap method followed by dry heating in the relaxed state in a pin tenter (3% under width and 6% over feed) for 1 minute at 350 F.

Example XI Pills per sq. inc

Without pill reducing treatment 1. With pill reducing treatment Example XII The fabric of this example is a crepe weave of 60 ends by 48 picks in the loom, woven from a mixed yarn of 50% polyethylene terephthalate, 1 /2 inch, 1 /2 denier per filament staple and 50% viscose rayon, 1 /2 inch, 1 /2 denier per filament staple, spun on the modified cotton system to a 40/2 cotton count, with a Z twist of 20 turns per inch in the singles and an S twist of 23 turns per inch in the ply. Fabric weight 5 /2 ounces per square yard. The pill test results follow:

Pills per sq. inch Without pill reducing treatment 9 With pill reducing treatment 5 Example XIII A sand crepe weave of 32 ends by 32 picks is woven from a cable yarn of polyethylene terephthalate, 2 /2 inch,

3 denier per filament staple, spun on the modified cotton system to a 30/3 cotton count. The slngles are given an 18 turns per inch 2 twist. A double ply is formed with an S twist of 12 turns per inch, the resulting double being plied with another singles in a Z twist of 22 turns per inch to produce the final yarn. The fabric weight is 6.8 ounces per square yard. Pill test results:

Pills per sq. inch Without pill reducing treatment 6 With pill reducing treatment 1 It will be obvious from the above that the finishing procedure of any fabric containing unrelaxed fiber may be varied widely and yet show a pill reduction when brushed and shrunk in accordance with the process of the present invention. The brushing and shrinking can precede any conventional finishing step, it may be applied after dyeing as the final finishing step, provided care is taken to avoid dye sublimation or it may be employed as an intermediate treatment. While use of a brush of the type described herein is the preferred method of producing exposed fiber disfiguration, other types of apparatus such as a sand brush, a despecker and a planetary or verticle napper operated with light energy to prevent breaking an excess number of filaments may also be employed for this purpose. In general shrinkage of a thermoplastic synthetic fiber can be conveniently accomplished by heating it at a temperature above its previous thermal history but below its point of fusion.

Many modifications will be apparent to those skilled in the art from a reading of the above description without a departure from the inventive concept.

What is claimed is:

1. A process for reducing the pill propensity of a fabric containing staple fiber produced from a synthetic fiber forming polymer which comprises disfiguring the fiber in the exposed crowns of the yarns by random flattening of their cross-sectional dimensions and thereafter locking the disfigured fibers within the fabric structure by compression with adjacent fiber at the points of asperity.

2. A process for reducing the pill propensity of a fabric containing staple fiber produced from a synthetic fiber forming polymer which comprises brushing the surface of the fabric gently with a rapidly revolving brush in a heel to toe contact and locking the disfigured fiber ends within the fabric surface by shrinking.

3. The process of claim 2 wherein the polymer is polyethylene terephthalate.

4. The process of claim 2 wherein the shrinking is accomplished by heating in an overfed pin tenter.

5. A process for reducing the pill propensity of a. fabric containing staple fiber produced from a synthetic fiber-forming polymer which comprises brushing the surface of the said fabric gently in a manner which provides heel to toe contact between the brush bristle and the said fabric surface and thereafter shrinking the said fabric.

6. The process of claim 5 wherein the polymer is polyethylene terephthalate.

No references cited. 

1. A PROCESS FOR REDUCING THE PILL PROPENSITY OF A FABRIC CONTAINING STAPLE FIBER PRODUCED FROM A SYNTHETIC FIBER FORMING POLYMER WHICH COMPRISES DISFIGURING THAT FIBER IN THE EXPOSED CROWNS OF THE YARNS BY RANDOM FLAT TENING OF THEIR CROSS-SECTIONAL DIMENSIONS AND THEREAFTER LOCKING THE DISFIGURED FIBERS WITHIN THE FABRIC STRUCTURE BY COMPRESSION WITH ADJACENT FIBER AT THE POINTS OF ASPERITY. 